There is substantial interest and available products which are used to corrosion-proof ferrous substrates. One particular type of product involves conversion of a rusted metallic surface to a usable surface. In general, there are two types of such rust conversion products. These products are rust conversion coatings and rust conversion products. Both products are similar in composition; however, the term "rust conversion coating" is generally reserved for those products which contain film forming polymers or copolymers. Commercial examples of such product types are Neutra-Rust.RTM. and Fertan.RTM.. A common property of these types of products includes the use of acidic aqueous emulsions (pH 1.2-3.0) which, when applied directly to rusted areas results in a black transformation of the rust. Distinctions between the products include viscosity, applicability and subsequent coating of the applied product. In general, such rust conversion products have the disadvantages of lower viscosities which leads to thinner drier films, and require that the treated surface be water rinsed and primed prior to overcoating. Conversely, rust conversion coatings do not usually have to be water rinsed and may serve as primers, or may themselves be incorporated into primer products. However, such products often exhibit decreased penetration of the rusted surface due to the sheer size of the polymeric resin.
Various prior published patents are known which are concerned with rust conversion or rust transforming compositions. For example, U.S. Pat. No. 4,510,181 discloses a corrosion protective coating layer formed on a metal surface by application of a composition comprising a vinyl monomer such as acrylate in combination with an initiator such as peroxide. In U.S. Pat. No. 3,474,070, coatings are prepared by reaction of a silane, a catalytic amount of an iron catalyst and water, the resulting coating then being polymerized by curing.
U.S. Pat. No. 4,421,569 describes the use of polymeric coatings on steel pipes which are provided by graft polymerization of a monomer onto the surface of the pipes. The composition includes a monomer and prepolymer along with a graft initiator and a catalyst such as a peroxide. In U.S. Pat. No. 4,459,324, a coating on a catalytic electrode is provided wherein the coating is formed from a catalyst dispersed in a semiconducting insoluble polymer matrix formed in situ on the substrate.
U.S. Pat. Nos. 4,424,079 and 4,451,296 to Barabas disclose rust removal compositions and processes. In U.S. Pat. No. 4,424,079, the composition comprises an aqueous solution of a vinylpyrrolidone/maleic acid polymer. The rust becomes incorporated into the coating during drying and the coating detaches itself from the metal surface for easy removal. In U.S. Pat. No. 4,451,296, the coating is an aqueous solution of a copolymer of maleic acid and a monomer having a double bond. The principle of this coating is the same as in U.S. Pat. No. 4,424,079. In U.S. Pat. No. 3,578,508, ferrous metal is corrosion-proofed with a solution obtained by treating chromite ore or other oxide with a gallic acid as a chelating agent. In U.S. Pat. No. 4,086,182, a rust transforming composition is provided which is an aqueous dispersion or emulsion of a synthetic binding agent and a complexing agent for the iron, the complexing agent being a polymeric esterification production of an aromatic oxycarboxylic acid containing phenolic groups and an acid anhydride. In U.S. Pat. No. 3,245,909, a non-corrosive lubricating composition is provided which comprises a lubricating oil, a high molecular weight nitrogen containing detergent type additive and a corrosion inhibiting amount of 2,4-dihydroxybenzoic acid. U.S. Pat. No. 4,041,814 to Zecher discloses a corrosion inhibiting composition which comprises a linear water soluble phenol-aldehyde resinous condensation product and a polyphosphate. U.S. Pat. No. 4,324,675 discloses protective additives for radiators which have iron based surfaces, the protective additive being an alkylene glycol based coolant inhibited with one nucleus-substituted benzoic acid and one conventional corrosion inhibitor. U.S. Pat. No. 4,325,744 to Panayappan et al discloses a method for cleaning metal surfaces comprising application of a thick aqueous solution of a water soluble polymer such as polyvinylpyrrolidone in a chelating agent such as ethylenediaminetetraacetic acid. U.S. Pat. No. 4,240,925 to Taft discloses a method for inhibiting corrosion by application of a composition comprising mixtures of organic anodic and cathodic corrosion inhibitors, in particular a phosphoric acid ester amide, amide-ester or combination thereof and a carboxylic, sulfonic, sulfate or acidic SH group containing compound. U.S. Pat. No. 4,241,011 describes antifreeze and coolant concentrates comprising an alcohol, a metal salt of a carboxysiloxane and an organic basic pH buffer material and a conventional corrosion inhibitor such as a hydroxybenzoic acid. U.S. Pat. No. 4,263,167 describes compositions which have resistance to oxidative degradation and which comprise a polyalkylene oxide having incorporated therein a bridged dimer of a hydroxyl substituted aromatic carboxylic acid.
In none of these prior art rust conversion processes, however, are there disclosures of compositions which are effective to provide in situ polymerization of a monomer under conditions whereby the iron contained in the surface is converted from the trivalent to the divalent state and whereby the monomer polymerizes within the rust surface to form an effective and permanent coating on the rusted surface.